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Published on: February 4, 2012
Accuracy of Influenza ICD-10 Diagnosis Codes in Identifying Influenza Illness in Children
James W Antoon1, Tess Stopczynski2, Justin Z Amarin1
1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee.
Insights
International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes for pediatric influenza show high specificity but moderate sensitivity. An ICD-10 diagnosis generally indicates a true influenza case in emergency department and inpatient settings.
Area of Science:
- Pediatric Infectious Diseases
- Health Informatics
- Epidemiology
Background:
- Accurate influenza diagnosis in children is crucial for surveillance and clinical management.
- Previous studies indicated variability in the accuracy of International Classification of Diseases, Ninth Revision (ICD-9) codes for identifying pediatric influenza.
- The diagnostic accuracy of the newer International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes for pediatric influenza remains largely unknown.
Purpose of the Study:
- To evaluate the accuracy of ICD-10 influenza discharge diagnosis codes in pediatric emergency department (ED) and inpatient settings.
- To assess the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ICD-10 codes for pediatric influenza.
Main Methods:
- A cohort study included 16,867 children in the ED and 17,060 inpatients across 7 US pediatric medical centers from December 2016 to March 2020.
- Molecular research testing for influenza was performed on nasal and/or throat swabs.
- Medical records were reviewed for ICD-10 discharge diagnoses and clinical influenza testing; molecular test results served as the reference standard.
Main Results:
- In the ED, ICD-10 codes demonstrated high specificity (98.0%), high PPV (88.6%), and high NPV (85.9%), but lower sensitivity (48.6%).
- In inpatient settings, specificity was 98.2%, PPV was 82.8%, sensitivity was 70.7%, and NPV was 96.5%.
- Diagnostic accuracy varied by patient age, influenza season, time to testing, and clinical setting.
Conclusions:
- Influenza ICD-10 discharge diagnoses in children are highly specific but only moderately sensitive for identifying laboratory-confirmed influenza.
- Despite moderate sensitivity, an ICD-10 diagnosis in the ED or inpatient setting is likely to represent a true influenza case.
- The accuracy of ICD-10 influenza codes is influenced by various clinical and epidemiological factors, necessitating careful interpretation.
Importance:
Studies of influenza in children commonly rely on coded diagnoses, yet the ability of International Classification of Diseases, Ninth Revision codes to identify influenza in the emergency department (ED) and hospital is highly variable. The accuracy of newer International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes to identify influenza in children is unknown.
Objective:
To determine the accuracy of ICD-10 influenza discharge diagnosis codes in the pediatric ED and inpatient settings.
Design, Setting, And Participants:
Children younger than 18 years presenting to the ED or inpatient settings with fever and/or respiratory symptoms at 7 US pediatric medical centers affiliated with the Centers for Disease Control and Prevention-sponsored New Vaccine Surveillance Network from December 1, 2016, to March 31, 2020, were included in this cohort study. Nasal and/or throat swabs were collected for research molecular testing for influenza, regardless of clinical testing. Data, including ICD-10 discharge diagnoses and clinical testing for influenza, were obtained through medical record review. Data analysis was performed in August 2023.
Main Outcomes And Measures:
The accuracy of ICD-10-coded discharge diagnoses was characterized using molecular clinical or research laboratory test results as reference. Measures included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Estimates were stratified by setting (ED vs inpatient) and age (0-1, 2-4, and 5-17 years).
Results:
A total of 16 867 children in the ED (median [IQR] age, 2.0 [0.0-4.0] years; 9304 boys [55.2%]) and 17 060 inpatients (median [IQR] age, 1.0 [0.0-4.0] years; 9798 boys [57.4%]) were included. In the ED, ICD-10 influenza diagnoses were highly specific (98.0%; 95% CI, 97.8%-98.3%), with high PPV (88.6%; 95% CI, 88.0%-89.2%) and high NPV (85.9%; 95% CI, 85.3%-86.6%), but sensitivity was lower (48.6%; 95% CI, 47.6%-49.5%). Among inpatients, specificity was 98.2% (95% CI, 98.0%-98.5%), PPV was 82.8% (95% CI, 82.1%-83.5%), sensitivity was 70.7% (95% CI, 69.8%-71.5%), and NPV was 96.5% (95% CI, 96.2%-96.9%). Accuracy of ICD-10 diagnoses varied by patient age, influenza season definition, time between disease onset and testing, and clinical setting.
Conclusions And Relevance:
In this large cohort study, influenza ICD-10 discharge diagnoses were highly specific but moderately sensitive in identifying laboratory-confirmed influenza; the accuracy of influenza diagnoses varied by clinical and epidemiological factors. In the ED and inpatient settings, an ICD-10 diagnosis likely represents a true-positive influenza case.
